In 2002, George Koonce, a nine-year linebacker in the NFL who had last played during the 2000 season, was confronted with a harsh reality. After holding out hope for almost two years that he’d be able to find a roster spot in the NFL, his wife, Tunisia, hit him with an ugly truth.

“George, you’re done,” she said. “It’s over.”

Koonce didn’t speak to her for several weeks, then took off, saying he was going to the beach for a few days.

On his drive back, he decided to take a turn at 75 miles per hour, “just to see what would happen.”

He flipped his truck but walked away. When he got home, he told Tunisia, “that part of me is dead now. I’m ready to move on.”

Koonce was one of the lucky ones.

“Is There Life After Football?” brings us inside the lives of NFL players to show why so many wind up in dire straits after their time on the field, from depression to debilitating lifelong injuries to catastrophic financial mismanagement.

While much-publicized concussions and head injuries account for some of the problems, they’re just one possible hardship of many for those who spend years slamming into each other at full speed.

“Since 2011, at least seven NFL players or former players have committed suicide,” the authors write, noting that one of these, Jovan Belcher, “also killed his girlfriend.”

Super Bowl quarterback Jim McMahon suffers from dementia. Hall of Fame running back Earl Campbell “can barely walk,” and “quarterbacking legend John Unitas lost the use of [his] hands and fingers.”

Ex-NFLers Curt Marsh and Jim Otto have both “lost limbs to football injuries.”

On the money end of things, Terrell Owens “is nearly penniless despite earning top dollar for years,” and “seven-time Pro Bowl defensive tackle Warren Sapp has filed for bankruptcy.”

The book seeks, among other things, to dispel the myth that everyone who plays in the NFL is financially set for life.

The average NFL career is only 3½ years long, and while even rookies currently earn around $400,000, the type of money we hear about for superstars — $22 million a year for Green Bay Packer Aaron Rodgers, for example — is rare. Most players never come close.

But however much money players make, it’s often far more than they know how to handle.

As a result, many players make bad financial decisions from the get-go, starting with reckless spending during their playing days — from Adam “Pacman” Jones, who talked of once spending “over a million dollars in one Las Vegas weekend,” to Andre Rison, who estimates he spent the same on jewelry.

“Around the locker room, players’ cars, clothes, houses and ‘bling’ are constantly scrutinized. If they’re not up to par, they’re ridiculed,” they write.

The authors cite former offensive tackle Roman Oben, who eschewed fancy cars for “a Toyota Land Cruiser with 68,000 miles on it. His teammates taunted him mercilessly.”

As such, players already fueled by lifelong dreams of luxury are persuaded to max it out. The previously frugal Koonce found himself making it rain in wasteful ways.

Former Tampa Bay Buccaneer Warren Sapp made $82,185,056 during his NFL career. In 2012, he had $826.04 in his bank account.Getty Images

“There is so much excitement; you have basically just hit the lottery,” he says in the book. “Once I made the roster, my first big purchase was a 1992 white Corvette with red interior for $38,000 … [Later] I bought a Mercedes and a Hummer. Players really go overboard on automobiles.”

As soon as the ink is dry on their first contract, players are overwhelmed by confusing advice from family and friends, who believe that they should be “helping” the player manage their finances.

After signing a $6 million contract with the Browns in 1985, quarterback Bernie Kosar hoped to secure an agent to handle his money.

But his father, who “didn’t really have a job after the mills closed,” wound up in the role instead and, according to Kosar, “was paying off his mortgage and … the house and cars” with the quarterback’s signing bonus.

Kosar thought he was helping his father out of a jam, but later learned that Dad had his own $1 million contract with the team. Between that, never-paid-back loans to family and friends, and bad investments spearheaded by same, Kosar lost about $15 million.

Bernie KosarGetty Images

Koonce tells of “an onslaught of requests from his family shortly after his first payday,” including from “aunts, uncles and distant cousins he barely knew.” Due to the familial connections, he found himself unable to say no. A trucking company he began with his sister cost him more than $500,000.

“Guys open up restaurants, and that is one of the most volatile industries you can get into,” said linebacker Bart Scott in the book. “[Friends] ask you to do it, and then you ask for their business plan and they say ‘What is that?’ Exactly.”

But if using family and friends as financial advisers is a bad move, actual advisers can be worse.

“Regulated or not, shady advisors have made quite a mark on the NFL financial scene,” the authors write. “Before closer scrutiny was instituted, at least 78 players lost more than $42 million between 1999 and 2002 because they trusted money to agents and financial advisors with questionable backgrounds.”

Adding insult to injury, the sketchy advice sometimes comes from former players themselves. One former player-turned-financial pro said that “he couldn’t reveal how much he was charging to manage [another] player’s tax-exempt municipal bonds ‘because of the Patriot Act.’” Turned out the adviser was “taking $146,000 every year.”

“Players don’t see their bills or keep track of their payments. They’re in the dark about taxes. They lose touch with their own money,” the authors write.

“You think of sharks in the ’hood, you think of gang bangers and drug dealers. You haven’t seen nothing ’til you step into some of these white-collar criminals,” said Scott, to which investment manager Ed Butowsky adds in the book, “I know many people who have had money wired out of their accounts to private equity accounts or into other accounts without their knowledge.”

The losses incurred by some players are staggering. Sapp made “$82,185,056 during his NFL career. He ended up with $826.04 in his bank account,” and filed for bankruptcy in 2012.

Former linebacker Keith McCants signed a $7.6 million contract in 1990 but tells the authors that he “bought a yacht, a mansion and a couple of cars. That ain’t a million dollars. That’s several million. I pretty much gave it away.”

Keith McCantsGetty Images

Even if a player manages to hang onto his money, figuring out what to do with himself in retirement can be just as challenging.

For one thing, few players actually “retire.” Koonce’s fate is more common: Players, over a long, drawn-out period filled with slowly diminishing hope, keep themselves in shape for a job that never materializes.

Once they realize the truth, then they must determine the next step.

For men who’ve been immersed in football to the exclusion of all else since high school, this can be crushing, as they have no idea how other people live, much less find work or spend 40 hours a week in a cubicle.

“[Retired defensive back] Troy Vincent recalls killing time in his unscheduled life by washing clothes every day until his wife told him that normal people don’t do laundry that often,” the authors write. “So he started cutting the lawn three times a week. He literally didn’t know what else to do.”

While many eventually find a path — Koonce got a Ph.D. in sports administration and is currently vice president of advancement at Marian University in Wisconsin, and Vincent is the NFL’s executive vice president of football operations — some simply drift, never finding a way to replace the excitement and totality of football in their lives.

None of this matters, however, if they’re physically incapable of working.

Few players actually “retire.” Koonce’s fate is more common: Players, over a long, drawn-out period filled with slowly diminishing hope, keep themselves in shape for a job that never materializes.

“More than 4,500 living players maintain that they have symptoms of football-related brain damage. That’s nearly a quarter of all living NFL alumni,” the authors write, later adding that “former players are over five times more likely than other men their age to suffer from dementia.”

But brain injuries are just one part of the problem, as an NFL career ravages not just the brain, but the body.

“Nine out of 10 former players wake up each day to nagging aches and pains that they attribute to football. About eight in 10 report that the pain lasts most of the day. Among younger retirees aged 30 to 49, one third say their work lives are limited in some way by the after-effects of injury,” write the authors. “Retired players are much less likely than their age peers in the general population to rate their health as excellent or good, and nearly 30% of NFL retirees rate their health as only ‘fair’ or ‘poor.’”

The league’s younger alumni, age 30 to 49, are “five times as likely” as their non-NFL age counterparts to have problems with mobility and strength, from walking stairs to lifting objects, and 15 percent of this group are “unable to work as a result of football-related disabilities.”

At 42, after nine years in the NFL, running back Brandon Gold “wakes up in pain, sometimes hardly able to move.” When he went for an MRI, the doctors asked, “What kind of car accident were you in?”

But despite the risks, which the players know well, the NFL’s tough-guy mentality resists change, and players have bristled against new rules designed to lighten the impact.

“I understand they want the sport to be safer,” All-Pro safety Troy Polamalu says in the book. “But eventually you’re going to start to take away from the essence of this game, and it’s not really going to be the football that we all love.”